1. Field of the Invention
This invention relates generally to a cable trolley, and particularly to a self-locking cable trolley particularly suited for use on the head stay of a sailboat, and the like, for manipulation by a working line attached to the luff of an associated sail in order to eliminate sag which may be in the sail.
2. Description of the Prior Art
A problem arises in the popular sport of sailing of keeping the jib sail from sagging relative to its associated head stay cable. While the common approach to eliminating sag from the jib is to tie the luff of the jib to the associated head stay, on larger boats especially it is difficult to reach the appropriate point in the jib and tie a tensioning line between the luff of the jib and the head stay. Further, it is becoming conventional to provide the jib with a furling cable passing along the luff of the jib in order to facilitate furling of the jib sail as by means of a furling drum. The use of such devices as furling drums are becoming extremely popular as they permit a relatively large sailboat to be crewed by only one or two persons. Thus, the problems associated with a sagging jib luff become even more important, inasmuch as such sagging places undesirable stresses on the furling cable and the fittings and bearings associated with the furling cable.
Accordingly, it is advantageous to provide a cable trolley which can be run up and down the head stay of a sailboat in order to place appropriate tension on a line attached to the luff of a sail associated with the head stay in order to remove sag from the sail.
Known cable trolleys, however, are not suitable to such an application. For example, U.S. Pat. No. 75,946, issued Mar. 24, 1868 to Miller, discloses a pulley block arrangement in which the weight of the load being lifted moves the pulleys into clutching engagement with a rope on which the pulley block arrangement is riding, with the pulley block being pivoted to its release position when the load is completely elevated. Such a load-responsive device, however, would have no application where it is desired to retain a cable trolley in a certain position in order to eliminate sag from a sail of a sailboat. While U.S. Pat. No. 408,702, issued Aug. 13, 1889 to Fiske, dislcoses a pulley arrangement which includes a clutch actuated by a separate length of line other than the line upon which the pulley arrangement is riding, the device is, like U.S. Pat. No. 75,946 discussed above, responsive to a load on the same endless length of cable on which the pulley arrangement is riding.
We are aware of the following additional patents that may be pertinent to the invention:
U.S. Pat. No. 623,328 filed on Apr. 18, 1899;
U.S. Pat. No. 3,470,982 filed on Oct. 7, 1969;
U.S. Pat. No. 3,756,565 filed on Sept. 4, 1973.